(19)

(11)

EP 0 770 220 A1

(12)

(43) Date of publication: 02.05.1997 Bulletin 1997/18 (21) Application number: 96913639.0 (22) Date of filing: 09.05.1996

(51) International Patent Classification (IPC):  G01T 1/ 20( . ) G01V 5/ 06( . ) (86) International application number: PCT/GB1996/001111 (87) International publication number: WO 1996/035964 (14.11.1996 Gazette 1996/50)

(84) Designated Contracting States: DE DK FR GB IT NL (30) Priority: 13.05.1995 GB 19950009755 (71) Applicant: Geolink(UK) Limited Dyce, Aberdeen AB2 0GZ (GB)	(72) Inventors: PRAIN, Kenneth, Alexander, Robertson Torphins Banchory AB31 4JS (GB) KNIGHT, John, Henry Crathes Banchory AB31 3JD (GB) (74) Representative: Orr, William McLean  Urquhart-Dykes & Lord, Tower House, Merrion Way Leeds LS2 8PA Leeds LS2 8PA (GB)